This invention is concerned with a mechanism for opening and closing at least one mould of a glassware forming machine of the individual section type.
The glassware forming machine of the individual section type is the dominant machine in the World for producing glassware containers such as bottles and jars. The principle of the machine is described in U.S. Pat. No. 1 911 119 in relation to a four-section machine whereas today six, eight, ten or even twelve-section machines are in use. Each section is an individual container-producing unit and has one or more blank moulds to which gobs of molten glass are fed to be moulded into parisons, and a like number of final moulds in which parisons are moulded into complete containers. The sections of a machine receive gobs in turn from a common source, operate in phased relationship to one another, and their output is delivered to a common conveyor.
Each section of a machine of the individual section type comprises a mechanism for opening and closing its blank mould or moulds and another similar mechanism for opening and closing its final moulds. Each such mechanism comprises a pneumatic piston and cylinder assembly having a piston rod, mould side portion supports arranged to support opposed side portions of at least one mould and movable between mould closed positions in which the side portions cooperate in defining a mould cavity in which molten glass can be moulded and mould open positions in which the side portions are separated, and a linkage system connecting said piston rod to said mould side portion supports arranged so that operation of the piston and cylinder assembly causes the supports to move between their mould open and mould closed positions. In the aforementioned U.S. Pat. No. 1 911 119, the mechanism of the blank mould (1) comprises a piston and cylinder assembly (28, 31) having a piston rod (32) operable to move supports in the form of holders (14) arcuately about a pivot shaft (25). The linkage comprises a link (33) pivoted to the piston rod (32), a three-armed rocking beam (34) one arm of which is pivoted to the link (33), links (35 and 36) pivoted to the other arms of beam (34), two vertical operation shafts (38) one adjacent each holder (14), two cranks (37) each secured to one of the shafts (38) and pivotally connected to one of the links (35 and 36), two cranks (40) each secured to one of the shafts (38), and two links (42) each pivotally connected to one of the cranks (40) and one of the holders (14).
As also described in U.S. Pat. No. 1 911 119, it is desired to start the motion of the mould side portion supports towards their mould closed positions at the maximum possible speed while cushioning the end portion of the motion towards their mould open positions. To this end, the air inlet passage (29) into one end cap of the cylinder (28) divides into two branch passages (52 and 53) one (52) of which is throttled by a plug (50) mounted on the piston (31) as the piston approaches the end of its stroke and the other of which contains check valve means (54) mounted in the passage into the cylinder. The check valve means is arranged to allow air under pressure to enter the cylinder (28) through the passage (53) to cause the supports to be moved towards their mould closed positions but to prevent exit of air through said passage. The check valve means comprises a closure member (54) and resilient means in the form of a spring urging the closure member into a position in which it closes said passage. The closure member (54) is displacable against the action of the spring by air pressure in the passage (53) to allow air to pass into the cylinder. The check valve means is mounted in a chamber defined by the end cap of the cylinder. Thus, air can enter the cylinder through the passage (53) and, once the plug (50) has left the passage (52), through the passage (52) but can only leave through the passage (52) so that the plug (50) entering the passage (52) causes a restriction and cushions the end of the motion.
Failure of the check valve causes the cushioning not to function and requires the check valve to be replaced before the machine sustains damage. However, replacement of the check valve is, as described below, time-consuming and difficult.
The various mechanisms of a section of a machine of the individual section type are mounted on a section frame which resembles a box. The piston and cylinder assembly is mounted within the box on a base plate of the frame whereas the moulds are mounted above the top of the box which supports the pivot shaft of the mould portion supports, the operating rods passing through holes in the top. Other operating mechanisms of the section are mounted in other holes in the top. In the event of the failure of a check valve, a mechanic removes two of said other operating mechanisms so as to gain access to the interior of the frame through the holes normally occupied by said mechanisms, then he unbolts the cylinder from the base plate and the end cap from the cylinder, and then he maneuvres the end cap away from the cylinder, removes the broken check valve and inserts a replacement. The mechanic must then re-bolt the end cap to the cylinder, re-bolt the cylinder to the base plate, and replace the removed mechanisms. All this must be performed in difficult conditions and possibly with other sections of the machine operating on one or both sides of him. The exchange of such check valves is, thus, time-consuming and causes considerable production losses. There is also a possibility of accidently introducing dirt into the valve or cylinder during this difficult operation.
It is an object of the present invention to provide a mechanism of the type described in which the check valve can be more quickly and easily exchanged.